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C++ API

Function File: phi = ls_setxor (phi1, phi2)

Calculate a level-set function for the set “xor” of the two domains given via phi1 and phi2. In other words, returned is a domain that contains all points that are in precisely one of the sets but not in both.

See also: ls_complement, ls_union, ls_intersect, ls_setdiff, setxor.

Demonstration 1

The following code

  n = 100;
  x = linspace (-7, 7, n);
  [XX, YY] = meshgrid (x, x);

  phi1 = (XX - 2).^2 + YY.^2 - 3^2;
  phi2 = (XX + 2).^2 + YY.^2 - 3^2;
  phi = ls_setxor (phi1, phi2);

  figure ();
  subplot (1, 2, 1);
  hold ("on");
  contour (XX, YY, phi1, [0, 0], "k");
  contour (XX, YY, phi2, [0, 0], "k");
  hold ("off");
  axis ("equal");

  subplot (1, 2, 2);
  hold ("on");
  imagesc (x, x, phi);
  set (gca (), "ydir", "normal");
  ls_sign_colourmap ();
  contour (XX, YY, phi, [0, 0], "k");
  hold ("off");
  axis ("equal");

Produces the following figure

Figure 1

Package: level-set